The present invention relates a method of operating a cooling- and heating circuit of a motor vehicle, and a cooling- and heating circuit for a motor vehicle.
Known cooling devices for motor vehicles with an internal combustion engine as a rule include a cooling- and heating circuit with several cooling medium channels in order to distribute and sometimes withdraw waste heat in the sense of a thermal management in the internal combustion engine and auxiliary aggregates such as for example turbo charger, transmission, generator, etc. Operational and environmental parameters, such as for the example the temperatures and/or the pressure conditions of the medium, the rotary speed, the load and the temperature of the internal combustion engine, the components and aggregates, as well as the temperature of the surrounding air and the passenger compartment are detected as input signals in an electronic control unit, and processed to form output signals for controlling of mainly electrically operated feeding and adjusting devices.
Such a cooling device is disclosed for example in the European patent document EP 0 499 071 81. It includes a first cooling medium circuit for cooling the internal combustion engine. Further, the machine oil and the charge air are cooled by additional oil cooler and charge air cooler by means of air. A control unit which has at least one microprocessor determines, depending on a plurality of measured condition variables the cooling power demand, the cooling power demand or heat demand of each individual aggregate or component of the cooling system and regulates the cooling medium flows individually, but with consideration of the whole system. For controlling the material- and heat flows, electrically controlled pumps and valves are provided. Further, additional, regulatable heating devices are connected to the cooling device, for example for heating of the passenger space or the wiping water of a windshield window wiping device, so that excessive heat energy can be used for heating when needed.
German patent document DE 37 38 412 81 discloses a device and a method for regulating the temperature of an internal combustion engine. The cooling medium circulates in a cooling circuit which is composed of several cooling medium channels. A first cooling medium channel leads through a bypass conduit, a second cooling medium channel leads through a main cooler of the internal combustion engine, and a third cooling medium channel leads through a heat exchanger which serves for climatization of the passenger space. The cooling medium distribution is performed by electrically operated valves at the branches of the cooling medium channel. In addition, in the cooling medium circuit a mechanical pump which is driven by the internal combustion engine to be cooled and electrically driven pump connected in series are arranged. During transportation of the cooling medium the mechanical pumps take a base load, while the feeding power of the electrical pump is controllable.
During a cold start the cooling medium, while bypassing the cooler flows through the bypass conduit back to the internal combustion engine, and is supplied in a lower region, namely in the region of the cylinder block. This small circuit brings little cooling power, so that the internal combustion engine reaches its operational temperature fast and the fuel consumption is reduced in advantageous manner. With increase of the cooling medium temperature a valve opens the second cooling medium channel with the main cooler, which when needed cooperates with a jalousie and a blower and withdraws the excessive heat of the cooling medium. A heating heat exchanger is arranged in a third cooling medium channel, and a part of the cooling medium flow is supplied through it when needed, for heating the passenger space.
If the cooling power of the heating heat exchanger is sufficient, the cooling medium channel with the main cooler is completely blocked. The excessive heat is supplied in this operational condition exclusively into the passenger space, which is desirable in particular at low exterior temperatures. During the heating phase of the internal combustion engine as a rule the heat generated during combustion is used for fast reaching of the operational temperature of the internal combustion engine, to lower the fuel consumption and to reduce the emission of damaging substances. The cooling medium flow through the heating heat exchanger is substantially reduced or completely blocked, so that during this time for cost of comfort only a small or no energy for heating of the passenger space is available.